Such apparatus is known from Australian Pat. No. 508,366. In that known apparatus, the adhesive is applied by spraying. This may result in irregularities, which will not be entirely compensated if rigid applying means are provided, which do not permit a control of the application rate. But a uniform application of an adhesive which is activated at elevated temperature is of special significance for a close adaptation to the surfaces of the profiled metal core. The adhesive is applied to vertical surfaces of the profiled metal core.
An exact, uniform application of adhesive is essential for a smooth fit of the profiled facings, which constitute the visible surfaces of the composite profiled bar and must be firmly secured without disturbing the uniformity of the adhesive layer.
If an adhesive which is activated at elevated temperatures is employed, a heating line is provided between the adhesive-applying station and the feeders for the profiled faacings. This is included.
The profiled metal core consists preferably of aluminum. The profiled facings consist suitably of polyvinylchloride, preferably of soft polyvinylchloride.
German Patent Specification No. 1,042,215 discloses box sections which consist of metal and are provided with projections on both sides of the side walls which are parallel to the plane of the frame, and C-section plastic elements provided on the inside and outside of the box sections. That design results in an improved heat insulation because insulating members are provided on the inside and outside.